Background: Generalized anxiety disorder is chronic and can be continued. The present study was conducted to examine the effectiveness of metacognitive therapy on cognitive-attentional syndrome and low cognitive confidence among female students of Shahid Chamran university of Ahvaz, who had generalized anxiety disorder. Methods: This was a quasi-experimental study with a pretest and posttest and a control group. The statistical population included all female students of Shahid Chamran university of Ahvaz, who were invited to participate in the present study by a phone call. First, for an initial diagnosis of the disorder, the generalized anxiety disorder scale was given to the students. Then, those individuals with a high score in anxiety questionnaire (cut-off point: 10 and above) underwent a structured clinical interview, and 28 individuals with generalized anxiety criteria were selected. The test group underwent ten 90-minute sessions of Wells metacognitive therapy. The questionnaire of cognitive-attentional syndrome and cognitive trust was used as a measurement tool in the pretest and the posttest. Data were analyzed by descriptive statistics and multivariate analysis variance test. Results: Multivariate variance analysis showed that the mean value of cognitive-attentional syndrome and low cognitive confidence in the test group significantly reduced compared to the control group. Conclusions: The findings revealed that MCT reduces the studied variables and indicated the effectiveness of meta-cognitive therapy on generalized anxiety.